THE PROTECTIVE EFFECT OF SPECIFIC MEDIUM ADDITIVES WITH RESPECT TO BUBBLE RUPTURE

A significant degree of cell damage is observed during suspension cell culture with air sparging. Protective agents can be added to the cult ure medium to protect the cells from damage. It has been observed that cells tend to adhere to air-medium interfaces and cell damage is main ly due to this cell-bubble interaction; protective additives have been found to prevent this cell adhesion to the bubble surfaces. In this a rticle, it is demonstrated that the interfacial tension between the ai r and medium is related to the effectiveness of the protective additiv es to prevent adhesion of cells to this interface. Five different type s of additives (Pluronic F-68, Methocels, dextran, Polyvinyl alcohol, and polyethylene glycols) were studied in an effort to determine their protective characteristics. Liquid-vapor interfacial tensions of the culture medium, with and without the additives, were measured by two d ifferent techniques (maximum bubble pressure method and Wilhelmy plate method). In addition, visualization techniques showed that in the pre sence of certain protective additives cells do not adhere to the bubbl e surface. Results obtained from these experiments indicate that the a dditives which rapidly lower the liquid vapor interfacial tension of t he culture medium also prevent adhesion of cells to the bubble surface . Experiments have also been conducted to determine the number of cell s killed due to bubble rupture, and it was observed that this number i s related to the amount of cells adhering to the bubble surface. (C) 1 995 John Wiley and Sons, Inc.